Loss Of Boost In 32gtr

[R32 Zilla]

I have an R32 GTR with R34 N1's, PFC, Blitz Dual SBC and lots of other stuff. It recently got tuned by Jim at CRD and made 285 AWKW @ 20psi. (Jim said his gauge was only showing 17 but it showed 20psi on my gauge on the street.)

After a trip home from Sydney I noticed that by my gauge I was only running 15psi and not 20 any more. I had not touched the boost controler or anything else. The PFC handset use to show about 1.35 to 1.4 bar when the gauge showed 20psi. Now at 15psi on the gauge it still shows about 1.28 bar on the handset. I tried to turn the boost up at the controller to see what sort of control I had but it required a big increase at the controller to get a small increase on the gauge. It didnt really want to go over 17-18 on the gauge.

So, at first i thought it may have been a leaking cooler pipe so i checked all them and they are fine now. I then removed the 'out' hose from the boost control solenoid in order to basically stop the controler from controlling the wastegates. This resulted in the turbos spinning freely to 20psi on the gauge where I back off. So from this i take it I can rule out a leak or a stuffed turbo ?? The strange thing was that the PFC hand controler showed 1.6 bar peak hold at 20psi on the gauge, when it use to only show about 1.4.

So I have a few problems here I think.

How did I loose 5psi on the gauge??

Does it mean my boost controller is playing up because when it is conected to the gates it wont allow over 15psi ??

Why is the PFC showing me strange and inconsistant figures ??

Any help with this would be great.

Thanks.

Tim.

Edited November 13, 2007 by R32 Zilla

[paulr33]

draw a diagram in ms paint of your setup

where does the pfc boost kit get its signal from

where does the guage you are reading get its signal from

[Beer Baron]

what brand of gauge is it?

[R32 Zilla]

Autometer boost gauge

There is a vacum line that goes from the intake manifold to the fuel presure reg (CRD fitted a new one). The boost gauge, PFC and the boost controller are all plumbed into this line.

Thanks.

[acsplit]

Throw the boost guage in the bin do you think the $70 boost guage would be more accurate than the $1500 one of the dyno.

seen many of these shit guages read wrong and change

[MRGTR911]

The best thing i ever did was buy a HKS EVC 5 ..... eLECTRONIC HOLDS BOOST LIKE CRAZY... Expensive. biut it does the job not like the older type boost controllers they shit themseleves...

[Beer Baron]

well it's quite possible the guage is faulty. also, with so many connections t'd off the one source you are in for a work of trouble. personally I'm not a fan of t'ing anything at all into the fuel reg pressure feed. as if something goes wrong with it you are heading for a massive lean out as soon as you hit boost. not good.

[R32 Zilla]

Ok Iam trying to find another vaccum source to T in a few things. I have 4 things that need vaccum. The PFC, boost gauge, boost controler and fuel presure reg. I cant seem to find any other source other then the one iam using now. I tried one that was close to the one iam using at the front of the motor but it hardly registered anything on the gauge. So where does everyone plumb in all these things ? If I could find just one more source then I could plumb 2 things into each source.

Thanks

Tim.

[femno]

There must be a simple explanation for this.

The vacuum sorce with little signal im guessing would be the one off the front throttle plate for the canister, which only works when the throttle is open.

Just take it back to CRD and get them to have a look. You stuffing around with it will most likely cost you more money because CRD will have to put it back right and you might even hurt something in the process.

Oh, and how does your PFC use the boost source when youve got the SBC?

[R32 Zilla]

The PFC must use the boost signal only for the boost reading on the handet ? I am not sure.

I have found another vacuum source at the rear of the motor. It is only small in diameter and it runs to a small unit on the firewall. Could this be used at all ?

I wish I could just take it back to CRD but it isnt that easy for me just now. I am spraypainter not a mechanic but I can normally sort through things like this.

Tim.